What's the real negotiation room on Bengaluru flats?

What's the real deal with negotiating property prices in Bengaluru? My kids are out, so I'm looking to sell our current place and get a manageable 2BHK, maybe around Hennur Road, like Keya Homes. I'm trying to understand the *true* all-in cost. How much can one realistically knock off the listed price? Are builders firm, or is there room for a spot discount? Also, what are the usual extras I should watch out for beyond stamp duty and registration? Any recent experiences?